Updated pam packages that fix a security vulnerability are now available.

PAM (Pluggable Authentication Modules) is a system security tool that allows system administrators to set an authentication policy without having to recompile programs that handle authentication.

2. Relevant releases/architectures:

Red Hat Linux 7.3 - i386Red Hat Linux 9 - i386

3. Problem description:

These updates fix a potential security problem present in the pam_wheel module. These updates correct a bug in the pam_lastlog module which prevented it from properly manipulating the /var/log/lastlog entry for users with very high user IDs.

The pam_wheel module is used to restrict access to a particular service based on group membership. If the pam_wheel module was used with the "trust" option enabled, but without the "use_uid" option, any local user would be able to spoof the username returned by getlogin(). The user could therefore gain access to a superuser account without supplying a password. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2003-0388 to this issue.

When manipulating the entry in /var/log/lastlog, which corresponds to a given user, the pam_lastlog module calculates the location of the entry by multiplying the UID and the length of an entry in the file. On some systems, the result of this calculation would mistakenly be truncated to 32 bits for users with sufficiently high UIDs.

All users of pam should upgrade to these updated packages, which resolve these issues.

4. Solution:

Before applying this update, make sure all previously released errata relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade. Only those RPMs which are currently installed will be updated. Those RPMs which are not installed but included in the list will not be updated. Note that you can also use wildcards (*.rpm) if your current directory *only* contains the desired RPMs.

Please note that this update is also available via yum and apt. Many people find this an easier way to apply updates. To use yum issue:

yum update

or to use apt:

apt-get update; apt-get upgrade

This will start an interactive process that will result in the appropriate RPMs being upgraded on your system. This assumes that you have yum or apt-get configured for obtaining Fedora Legacy content. Please visit http://www.fedoralegacy.org/docs for directions on how to configure yum and apt-get.